[PATCH 0/9] boot: add imagemap on-demand image loading from storage

[Daniel Golle <daniel@makrotopia.org>]

This series adds "imagemap", a small layer for reading FIT images
directly from storage on demand instead of copying the whole image
into RAM first. It keeps a translation table of the byte ranges
already loaded, so a header probe, signature verification and the
final load can reuse a single read, and it hooks transparently into
fit_image_load() so all existing verification and decompression paths
run unchanged for both RAM- and storage-backed images.

An imagemap device is created over a partition of a block device. That
covers more than raw disks: an MTD partition is reached through
mtdblock and a UBI volume through ubiblock, each exposed as a named
block-device partition, so imagemap carries no storage-specific code
of its own. NAND bad-block handling and wear-levelling stay with UBI,
as they do elsewhere in U-Boot; on NOR a partition is read linearly
with end-to-end integrity guaranteed by the FIT hash or signature.

To make those two paths reachable and testable, the first patches fill
in the missing block devices: a non-NAND MTD master now gets an
mtd_blk device automatically (patch 1), and attaching UBI now binds a
ubi_blk device on any flash (patch 3, which makes the SPI-NAND-only
eager binding redundant, dropped in patch 4).

The read path is built on the SPL struct spl_load_info abstraction and
a new spl_load_region() helper. imagemap is full-U-Boot only; the SPL
FIT loader is unaffected.

Testing (sandbox): "ut imagemap" (13 tests) covers the
translation-table core plus real end-to-end reads of a NOR partition
through mtd_blk and a UBI volume through ubiblock; a CONFIG_IMAGEMAP=n
build is unaffected.

On hardware it has been tested end-to-end on a BananaPi R3 (mt7986),
booting a dm-verity-protected rootfs from every storage path the board
exposes: eMMC and SD (block partition), SPI-NAND (UBI volume via
ubiblock) and SPI-NOR (raw MTD partition via mtdblock). The first
in-tree consumer, a bootmeth for OpenWrt-style FIT firmware, will
follow as a separate series.

This series began as part of a combined RFC that also carried the
OpenWrt boot method and its bootdevs [1]. Following the review there
it has been reworked substantially:

  - Build on U-Boot's existing SPL external-data loading path rather
    than a new abstraction: imagemap now uses struct spl_load_info and
    a new spl_load_region() helper (suggested by Marek Vasut).

  - Do not extend the bootm command with a storage source; on-demand
    loading hooks into fit_image_load() transparently, and the in-tree
    consumer is a bootstd boot method reached through
    bootflow/bootdev/bootmeth rather than new bootm syntax (per Tom
    Rini).

  - Move the storage-backed path out of the long fit_image_load() into
    its own helper, gated with if()/tools_build() instead of an inline
    #if (per Simon Glass).

  - Collapse the three storage-specific backends (block, MTD and UBI)
    into a single block backend: NOR is read through mtd_blk and
    SPI-NAND through UBI/ubiblock, so imagemap holds no
    storage-specific code.

  - Send the on-demand loading core on its own; the OpenWrt boot
    method, the MTD/UBI bootdevs and board enablement follow as
    separate series once this lands.

In order to test imagemap end-to-end with the intended bootmeth user
I'm still relying on the downstream install-uuid mechanism of [2],
which [3] could supersede. Both have stalled right now.

[1] https://lore.kernel.org/u-boot/cover.1771275704.git.daniel@makrotopia.org/
[2] https://github.com/open-source-firmware/flat-image-tree/pull/40
[3] https://github.com/open-source-firmware/flat-image-tree/pull/44

Based on u-boot/next.
Daniel Golle (9):
  mtd: bind an mtd_blk device for non-NAND MTD masters
  mtd: nand: sandbox: forbid sub-page writes
  cmd: ubi: create a ubi_blk device when attaching UBI
  mtd: nand: spi: drop the eager ubi_blk binding
  boot: add imagemap on-demand loading from storage
  boot: fit: support on-demand loading in fit_image_load()
  configs: sandbox: enable imagemap and its storage backends
  test: boot: add imagemap unit tests
  doc: imagemap: document on-demand loading framework

 MAINTAINERS                      |   9 +
 arch/sandbox/dts/test.dts        |  29 ++
 boot/Kconfig                     |  16 +
 boot/Makefile                    |   2 +
 boot/bootm.c                     |  70 +++-
 boot/image-fit.c                 | 109 +++++-
 boot/imagemap.c                  | 451 +++++++++++++++++++++
 cmd/ubi.c                        |  27 ++
 configs/sandbox_defconfig        |   6 +
 doc/develop/imagemap.rst         | 100 +++++
 doc/develop/index.rst            |   1 +
 drivers/mtd/mtdcore.c            |  24 ++
 drivers/mtd/nand/raw/sand_nand.c |   2 +
 drivers/mtd/nand/spi/core.c      |   3 -
 include/bootm.h                  |   2 +
 include/dm/uclass-id.h           |   1 +
 include/image.h                  |   2 +
 include/imagemap.h               | 136 +++++++
 include/spl.h                    |  47 ++-
 test/boot/Makefile               |   2 +
 test/boot/imagemap.c             | 645 +++++++++++++++++++++++++++++++
 test/cmd_ut.c                    |   2 +
 22 files changed, 1671 insertions(+), 15 deletions(-)
 create mode 100644 boot/imagemap.c
 create mode 100644 doc/develop/imagemap.rst
 create mode 100644 include/imagemap.h
 create mode 100644 test/boot/imagemap.c


base-commit: 8841b7b292c74864acf4ed0bd8ce05839252c1f2
-- 
2.55.0